Method and apparatus for making dieexpressed metal sponge of group iv, subgroup a



April 1960 D. s. CHISHOLM ET AL 2,932,565

METHOD AND APPARATUS FOR MAKING DIE-EXPRESSED METAL SPONGE OF GROUP IV, SUBGROUP A Filed April 17, 1957 2 Sheets-Sheet 1 I N V EN TORS. Doug/a6 6. Chisholm Dan E Hal/ ,q'rrok NE vs April 12, 1960 D. s. CHISHOLM ET AL 2,932,565

METHOD AND APPARATUS FOR MAKING DIE-EXPRESSED METAL SPONGE 0 Filed April 17. 1957 F GROUP IV, SUBGROUP A 2 Sheets-Sheet 2 INVENTORS. Doug/0s 62 ChIIs/m/m Don F: Ha// WMA arrog/vg s METHOD AND APPARATUS FOR MAKING DIE- EXPRESSED METAL SPONGE F GRQUP IV, SUBGROUP A J' Douglas s. Chisholm and Don F. Hall, Midland, Mich,

assiguors to The Dow Chemical Cornpany, Midland,.

Mich a corporation of Delaware 7 Application April 17, 1957, Serial No. 653,?91 11 Claims. (Cl. 75 -84.1)

This invention is directed to the production of metals of group IV, subgroup a, of the periodic table of elements. More especially it is directed to an improved method of an apparatus for reducing such metals from their saltsby the action of a reducing metal to form ingots having a protective sheath thereabout comprising a salt of the reducing metal.

SEES Patent 0 P ce magnesium chloride and the titanium or zirconium sponges I p As a method of removing the reaction product comprising titaniuniio'r zirconium sponge and some entrained magnesium chloride formed on the rotatable disc according to the British patent, there is described an 1 air-cooled scraper comprising a flat-sided, or preferably 1 somewhat edged, scraper head carried on the end of a reciprocating air-cooled hollow shaft. The shaft is housed in a tube which is aflixed to the reaction chain beron one end to'a supply of cooling air on the other end. 'The shaft is reciprocable by means of a crankshaft pivotably attached'to an eccentric drive gear. The

reciprocable scraper head is positioned to remove'the reactionproduct from the surface of the rotatable disc. Thereaction product falls to the bottom of the reaction vessel which-contains the magnesium "chloride that has drained from the reaction product while on the disc.

'Heretofore, metals of subgroup IVa have been largely produced as a sponge by the reduction a halide of the metal to be produced, .e.g., titanium tetrachloride, by. contacting a pool of molten reducing metal, e.g.,

magnesium, by the halide in vapor form in a reactor. r

A number of disadvantages are inherent in this practice which limits its usefulness. Among such disadvantages are: The metal produced adheres tenaciously. to the walls of the reactor soi that the reactor must usually be collapsed or destroyed to release the metal. The reaction also tends to get out of control and cause the reducing metal to vaporize, the resulting vapor then reacting with some of the vaporous halides to produce the reduced metal as dust-like particles. These particles have small value at present since they do not lend themselves well 4 The bottom of the reaction chamber shown in the British patent is slanting or hopper-shaped to aid in the removal of the reaction product. The major portion of the magnesium chloride, in the reaction product which is a liquid at the temperature of the reaction may be sep- [arated from the sponge by the provision of a drain means.

' A suggested means for removing the reaction product from the reactor described'in the British patent to which reference is made hereinabove comprises a screw conveyor positioned along the slanting bottom of, the reactor to carry the. reaction product upwardly and outwardly from the body of the magnesium chloride and, by means of aninclosing barrel having an outlet adjacent to the outer ends-thereof, to drop the reaction product into a to the formation of metal rods, blocks, or other massive forms. Furthermore, known methods of producing sponge metals of subgroupIVa have not been continu-.

ous since the reactive nature of the metal sponge has heretofore required batchwise operation to permit cooling prior to the removal of the metal from the'reactor.

In British' Patent 734,166 and in our copending US.

application Ser. No. 315,604, filed Oct. 20, 1952, there is described and claimed a method of an apparatus for reducing a titanium or zirconium halide vapor with magnesium metal at a smoldering temperature to form a sponge of the metal. According to the method therein described, magnesium in the form of particles is deposited upon a supporting surface, such as a steeljapron,

receiver through an outlet provided therefor near the outer end of the screw, a

, ,Although --British Patent 734,166 provides an improved. and theretofor novel method of producing titanium and zirconium, the method provided therein for the removal of the reaction product fromthe reactor is not fully satisfactory where itis desirable that the metal be produced in ingot formor. a continuous operation is desired since titanium and zirconium must adequately be protected from air during the production thereof.

There is a desideratum in the art of producin'g rnetals of subgroup IVa for a continuous process during which the metal is produced as an ingot protected from the attack of air.

or a circular table, in an atmosphere containing an inert gas and a heated titanium or zirconium halide vapor. The surface is preferably moving andis coole'din rela-' tion to the ambient atmosphere containing the halide vapor. The magnesium particles are caused to burn at a smoldering rate by controlling the temperature'of the surface where. the titanium or zirconium and the by-. product magnesium chloride are-formed. Some of the magnesium chloride drains from the titanium or zirconium metal and falls to the floor of the reactor wh1le the metal as a part of the reaction product and is removed therefrom later by a. suitable means, e.g.,' vacuum distil j The 'present invention is predicated on the discovery that a metal of subgroup IVa, viz, titanium, hafnium,

thorium, and zirconium produced by the reduction of its halides by-areducing metal on-a moving hearth such as for ieqgample that described in British Patent 734,166, a can be di e-expressed to produce an ingot. The preferredembodiinent of the inventionjproduces an ingot havinga core consisting largely. of the produced metal incased' inja protective sheathconsisting largely of the -by-product halide thereby protecting the product from attack andproviding a continuous method of operation.

. remainder of the magnesium chloride is entrained in the The invention then comprises a methoda'nd apparatus for die-expressing ametal of subgroup IVa which is producedon a hearth by' r'educt'ion thereon of ahalide of 'thc met al'to be produced by the action of a reducing.

metal; In the preferred embodiment the die-expressed iinetal thereby produced is incased in a protective sheath composed largely of the halide of the reducing metal. The accompanying drawing illustrates a preferred em- "bodiment of "the invent'ion exemplifying thejreduction of titanium tetrachloride by magnesiumfmetal;

titanium halide'taltes pl'ace on the disc forming thereon Figure 1 of the drawing shows: an elevational sec- 7 tion of an apparatus of the invention havinga reciprocat'ory ram,- rotary conefand dies associated therewith, the

Patented Apr. 12 1960 ,vides a supporting means for the shaft.

Referring to the drawing and particularly to Figurel in greater detail there is shown furnace setting 7 in which is positioned reaction chamber 8. Inert gas is provided by inlet 9. Gas burners 10 and ll'provide heat for reaction chamber 8. Reservoir 12, through feed line 13 having valve 14 therein, supplies titanium tetrachloride to the reaction chamber. Hopper 15, by means of feed line 16, barrel 17 which has screw 18 operating therein and 'driven by a means not shown, and feed line 19 containing valve 20 therein, supplies the particulated' magnesium to reaction chamber 8. The hearth in the form of hollow cone 21 is integrally secured to and is supported by rotatable shaft 22. In shaft 22 israir-cooling channel 23, connected to hollow interior 24 of the cone, and attached to a source (not shown) of 'incoming'cooling air. Annular channel '25 about channel 231within shaft 22 provides for the return of spent cooling 'air' to air outlet 26. Bearing 27 in bearing support 28 pro- Gear box 29, powered by motor 30, rotates shaft 22. Gear box 31, powered by motor 32, reciprocates ram 33 by means of crank 34, connecting rod 35, and wrist-pin 36 at the upper end of rod 37 whichpasses through stuifing box 38 and guide 39 below which it,is secured to the upper end of ram 33. Ram 33 has nose 40 in sliding contact with cone 21. By means of timer 41. connected to a source of current (not shown) by electrical lines 42, and by lines 43 and 44 to motors 30 and 32, respectively, the rotary action of driveshaft 22 and the reciprocatory action of ram 33 are timed to act alternately for predetermined periods of time?" In order that driveshaft 22 and ram 33 have operable clearance, it is necessary that driveshaft 22 be positioned so that it passed ram 33 without interfering with its own action or that of the ram. clearance may be provided by a number of means among which is that of merely tipping driveshaft 22 slightly so' that it is not in the path of ram 33. Although, as the result of such slight'tipping, ram 33 does not move exactly radially of cone 21, the practical results obtained by the apparatus for removal of the reaction product from the surface of cone 21 is not affected. i i Housing 45 is maintained inan upright position by support 46. Sliding engagement is provided between housing 45 and rod'37 by hearing 47 and betweenhousing 45 and ra'm33by bearing 48. I o V a Elongated die 49 defines a rectangular passageway and enlarged die 50 defines a cylindrical passageway which is aligned with the passageway of die 49 and which leads out of reactor 8. Guide plate 51',having a smooth exposed vertical face, is secured to the .wall ofr'eactor-8 so as to extend substantially thereacross in such position ameter at least as large as, and preferably slightly larger than, the diagonal of the square defined by die 49. The shape of nose 40 of ram 33 is roughly that of the entrance into the passageway of die 49 with operable clearance for reciprocating therein. However, the ram may merely advance to a position flush with the entrance to die 49 and in such case the nose 40 of the ram need have only the general shape of the die opening. Drain line 55 provides a means for removing molten magnesium chloride from reactor 8.

The practice of the invention will be described according to the embodiment employing titanium tetrachloride and magnesium using the apparatus of Figure 1.

In practicing this embodiment of the invention, pulverulent magnesium of 20 to 200 mesh and preferably from 30 to 100 mesh (U.S. standard sieve series) is placed in hopper .15. A supply of titanium tetrachloride is placed in reservoir 12. By means of gas burners 10 and 11, furnace setting 8 is heated to bring thecontents of reactor 8 above the melting pointof the magnesium chloride formed but below a temperature which will cause rapid or flaming reaction of the magnesium metal. A temperature between 600 and 900 C. is employed. The recommended temperature is between 708 and 850 C. .The magnesium from. hopper 15 is caused to fall on cone'21 by operating screw 18 in barrel 17 and titanium tetrachloride is drawn into the reactor through line 13, The reactor chamber 8, thus being heated, the titanium tetrachloride becomes vaporous therein and is disseminated throughout the reaction chamber. The magnesium powder on the cone reacts with the ambient titanium tetrachloride vapors to form the reaction product comprising a reaction mixture of titanium metal and liquidv magnesium chloride.

Ram 33, actuated by timer 41, advances downwardly, pushing the reaction product from cone 21 (which is stationary during the action of the ram) into die 49. The ram is caused to begin its movement more or less radially at a point on a relatively short circumference of the cone and to push outwardly toward the cones periphery, that is, towards the greatest circumference of the cone. The ram thereby pushes the reaction product at predetermined time the conescenter toward its periphery and back again. A

suitable arrangement of the apparatus of the invention, for example, is a cone having a circumference of 100 inches which moves through an angle of 72 at each partial turn and stops for about 4 seconds for the ram to operate. In

other words, the cone stops rotating 50 times during one complete rotation of 360 and the ram makes 15 complete reciprocatory trips along a radius of the cone each minute.

The reaction product which forms on cone 21 is composed essentially of titanium as a metal sponge and magthat the 'smooth face is in sliding engagement. with that vertical face of ram 33 which is farthest removed from cone 21, and thereby guides ram'33 in its substantially vertical path as well as prevents reaction materialybeing removed by the ram, from rolling off rectangular nose 40of ram 33 toward the side of reactor 8 instead of being expressed into-die 49. 1 p

Cooling jacket 52, having inlet 53 ..and outlet 54,

around die 50 and thelower portion of die 49 provides acooling means for the dies. A preferred arrangement is-to have.die'49, the first die, define a square, and die ;50, the second die, define roughly, a circle having adinesiumfchloride in the molten state. As a result of its molten state, a large portion of the magnesium chloride drains from the titanium sponge on the cone and deposits at the bottom of the reaction chamber where it is removed as desired through drain line 55. An appreciable amount of magnesium chloride, however, remains entrained in the interstices of the titanium sponge. That magnesium chloride which does not drain from the reaction product and is entrained in the titanium sponge is expressed together with the titanium into die 49 by ram 33. Both solidify before leaving die 49 due to cooling jacket 52 .and are expressed on into die 50.

The solidified reaction product emerges from die 50 as an ingot comprising predominantly titanium core 56 inr cased in predominantly magnesium chloride sheath 57 as shown in cross-section in Fig. 3. The core is usually at least 80 percent titanium and the sheath is usually at least 90 percent magnesium chloride.

The formation of the sheath may be explained as follows: The subgroup IVa metal sponge in thereaction product, having interstices therein, is somewhat compressed longitudinally while being expressed through first die 49 by the ram. A substantial portion of the entrained molten salt of the reducing metal, i.e., magnesium chloride in the illustration, is squeezed from the interstices so that it is forced ahead of the titanium metal as it passes through elongated first die 49., Upon reaching the enlarged cross-section provided by second die 50, it is forced laterally beyond the periphery of the metal sponge defined by first die 49 andfills the space between the periphery of the metal sponge defined by first die 49 and the confining limits of the extended portion of second die 50. The somewhat compacted metal sponge moving along the inner portion of the passageway of second die 50 retains the, form of first die 49. Since the dies are provided with cooling means, that salt thus forced into the space about the predominantly metal sponge inner core solidifies in the passageway of die 50 to incase the metal sponge in a protective sheath. An ingot is thus extruded comprising the titanium core and metal halide sheath.

The die-expressed extruded ingot may be cut into convenient lengths by known means, or the operation may be interrupted after predetermined periods of time to provide convenient lengths of the ingot.

A modified means for achieving alternate rotation of cone 21a, which is similar to cone 21 of Fig. l and reciprocation of ram 33a, which is similar to ram 33 of Figure l, is shown in Figure 2. Hydraulic cylinder assembly 60, having. air-controlled valves therein (not shown), is connected to a source of hydraulic fluid (not shown) by means of lines '61 and 62. The air-controlled valves therein are timed to admit hydraulic fluid to reciprocate rod 37a and ram 33a attached thereto by timer 63 connected to cylinder 60 by electric lines 64. Electric lines 65 lead to a source of electric current (not shown).

To rarn 33a is secured fixed collar 66. Adjacent to and supported by fixed collar 66, when ram 33a is in a retracted position, is sliding collar 67 to which is attached arm 68 in which is eyelet 69. Collar 67, by means of cable 70 inserted in eyelet 69, and threaded through pulley 71, which is under continual tension by a spring 72 seto engage the drive gear of shaft 22a, therefore to cause it to turn until ram 33a is again advanced.

Figure 4 shows a portion of a modified apparatus for practicing theinvention. Cone 21b is shown positioned in reactor 8b with cover removed. Cone 21b is driven from below by means not shown. Ram 33b reciprocates substantially from the center of cone 21b to the edge thereof by driving means (not shown) attached to rod' 3712 which is synchronized to operate alternately with the cone-driving means to force reaction product formed on the surface of cone 21b into die 49b.

Although the practice of the invention has been described according to .the drawing for reducing TiCl by Mg metal, it is understood that the invention contemplates producing any subgroup IVa metal reducible from its halide by a metal more eleetropositive than the subgroup IVa metal, e.g., the alkali and alkaline earth 'metals. It is also understood that the invention contemplates variations of the method described and apparatus shown which fall within the purview of the invention. Instead of a cone, a flat disc or a concavo-convex shaped disc having the convex face upwardly disposed may be employed. When a cone is employed as in the example, the downwardly sloping face adjacent to the ram need not be positioned as shown in the drawing but may be positioned at any desired angle between about 20 and cured to bracket 73, is'caused to follow fixed collar 66 7 actuated by a conventional over-running clutch (not shown) which is also inclosed in housing 76. The overrunning clutch is attached to the end of arm 77 which extends into housing 76. In the other end of arm 77 V is eyelet 78 into which is made secure the ends of both cable 70 and spring 72.

When the apparatus of Figure 2 is in operation, cone 21a is made to rotate, as by a gear box and a motor similar to those shown in Figure 1, while ram 33a and fixed'collar 66 are retracted. When ram 33:: and fixed collar 66 advance by the hydraulic pressure in cylinder 60, slideable' collar 67 also advances due to the tension exerted on collar 67 by spring 72, but is stopped when arm 63 strikes stop 74. Collar 67, being secured by cable 70 to arm 77, permits spring 72 to move arm 77 counter-clockwise when collar 66 advances, thus causing the over-riding clutch inclosed in housing 76 to disengage the driving mechanism alsoinclosed in housing 76. Shaft 22a, therefore, stops turning while ram 33a continues to advance downwardly, pushing the reaction prodabout to the horizontal. The included angle of the cone employed may be any angle of less than 180, although an included angle of between about 90 and is preferred. v

It is necessary that the ram perform a scraping action against the face of the cone with which it is in contact. The contacting faces of the cone and ram need not be exact counterparts of each other, i.e., need not be mirror images of each other, but it is desirable, particularly where a cone having a relatively small included angle is employed, that the cone be contoured into flattened sectors corresponding in angular width equal to the distance the cone is advanced during one rotary movement. Instead of flat sectors, they may be concave resulting in a radially fluted cone surface, and the adjacent surface of the ram be convex to form substantially a mating contacting surface.

Although two concentric dies are described according to the drawing, one die may be employed, thereby forming an ingot of unsegregated subgroup IVa metal and a halide of the reducing metal.

In practicing the invention according to its preferred embodiment there is thus produced convenient length sticks or ingots of a metal extrudate which contains a core of at least 80 percent titanium or other subgroup IVa metal protected by an outer shell or sheath of the by-product halide against corrosion. The sticks of extruded metal thus formed are particularly suitable for use according to our co-pending application Serial No.

649,809, filed April 1, 1957, wherein an ingot thus formed a is made a first electrode and fed into an atmosphereof inert gas in which is a second electrode in the form of a rotating rod or disc, which may be either impure titanium, i.e., a cylindrical rotating rod similar to the first electrode or of substantially pure titanium, and striking an electric are between the nose of the-first electrode and preferably the periphery of therotating electrode to melt the first or non-rotating electrode to form titanium prills intermixed with the halide salt from which the latter can bereadily removed.

As an alternative mode of operation, the extruded metal of the present invention need not be cut into lengths, but may be fed, by employing a continuous means, directlyinto the apparatus described inthe copending application mentioned ingthe paragraph above.

Having described the invention, whatis claim'ed and desired to be protected by Letters Patent'is':

1. In' an apparatus for the production of a subgroup IVa metal sponge containing by-product reducing metal reciprocating said ram, and' a die substantially aligned with said ram near the end of its radially outward movement to receivethe subgroup, IVainetal sponge and byproduct halide.. a

' 2. The apparatus of claim 1 wherein said die is provided with a'coolingmeans'l i 3., In anapparatus forthejpr notion of a metal of a subgroupIVa, having) a reaction chamber provided ,with a. heating means and afrheans for2 causing a flow of. an inert gas therethrough', n means for providing a [halide of subgroup IVa metal anda pulverulentreducing metal therein, and a rotatable circular hearth positioned "therein to receive" the reducing metal, the improvement comprising a reciprocatory'ram positioned to move substantially radially outwardly on the face of said surface toward its periphery to remove reaction product formed on said hearth, a synchronized-driving means for rotating said hearth and reciprocating said ram to efiect alternate operation thereof, and associated with said ram and substantially aligned therewith a first elongated die opening into a second elongated die, said second die being substantially concentric with and of larger crosssection than said first die,

4,.The apparatus of claim 3 wherein a guide plate is secured to the inner wall of said reaction chamber and positioned in sliding engagement with the side of said ram which is opposite to the side in contact with said circular hearth to guide the reaction product into said first die.

5. The apparatus oflclaim 3 wherein said first die defines a rectangular passageway therethrough and said ,aeeases second die defines a substantially cylindrical passageway therethroughhaving a diameter atleast as large as th diagonal of said rectangular passageway.

'6. The apparatus of 'claim 3 wherein said circular hearth is a cone having its apex upwardly disposed and "having an included angle of at least 7. The apparatus of claim 3 wherein said circular hearth is a concavoconvex disc having its convex side upwardly disposed.

8. The apparatus of claim 3 wherein said circular hearth comprises a series of flattened sectors having an angular width equal to the angular movement of the cone during a single rotary advancement.

9. The apparatus of claim 8 wherein said sectors are concave and the adjacent face of said ram is convex to form substantially mating contacting surfaces.

10. In the method of producing a metal selected from the group consisting of hafnium, titanium, thorium, and

' zirconium from a halide by means of a reducing metal selected from the group consisting of the alkali and alkaline earth metals wherein the, reducing metal is continuously caused to fall on a rotatable surface in an atmosphere comprising an inert gas heated to a temperature not less than the melting point of the halide of the reducing metal being produced to effect a reaction between the reducing metal and the halide in the vapor state on the rotatable surface to produce a reaction product comprising the metal sponge of the metal to be produced and the halide of the reducing metal, the improvement consisting of alternate rotation of the surface and removal of a portion of the reaction product formed thereon, said .removal being accomplished by pushing a portion of the thus-produced reaction product radially outwardly to the periphery of the said surface, and die-expressing the reaction product thus removed.

11. The process of claim 10 wherein the halide, from which the metal selected from the class consisting of hafnium, titanium, thorium, and zirconium is produced, is titanium tetrachloride and the reducing metal is pulverulent magnesium.

References Cited in the file of this patent UNITED STATES PATENTS 

10. IN THE METHOD OF PRODUCING A METAL SELECTED FROM THE GROUP CONSISTING OF HAFNIUM, TITANIUM, THROIUM, AND ZIRCONIUM FROM A HALIDE BY MEANS OF A REDUCING METAL SELECTED FROM THE GROUP CONSISTING OF THE ALKALI AND ALKALINE EARTH METALS WHEREIN THE REDUCING METAL IS CONTINUOUSLY CAUSED TO FALL ON A ROTATALE SURFACE IN AN ATMOSPHERE COMPRISING AN INERT GAS HEATED TO A TEMPERATURE NOT LESS THAN THE MELTING POINT OF THE HALIDE OF THE REDUCING METAL BEING PRODUCED TO EFFECT A REACTION BETWEEN THE REDUCING METAL AND THE HALIDE IN THE VAPOR STATE ON THE ROTATABLE SURFACE TO PRODUCE A REACTION PRODUCT COMPRISING THE METAL SPONGE OF THE METAL TO BE PRODUCED AND THE HALIDE OF THE REDUCING METAL, THE IMPROVEMENT CONSISTING OF ALTERNATE ROTATION OF THE SURFACE AND REMOVAL OF A PORTION OF THE REACTION PRODUCT FORMED THEREON, SAID REMOVAL BEING ACCOMPLISHED BY PUSHING A PORTION OF THE THUS-PRODUCED REACTION PRODUCT RADIALLY OUTWARDL TO THE PERIPHERY OF THE SAID SURFACE, AND DIE-EXPRESSING THE REACTION PRODUCT THUS REMOVED. 